Galin



NOV. 17, 1953 GALlN 2,659,549

CABLE-FEED MECHANISM FOR CABLE SHIPS Filed July 1, 1950 F/GZ 1/ i W I r1% 4 10 I5 16 I7 73 INVENTOR Marc Galm BYMW ATTORNEY Patented Nov. 17,1953 stares re- EN T OFFICE CABLES-FEED MEGH-ANISM FORCABLErSHIPS I'MarcGalin, Le'Canet-Marseille, France, assignor to 'Etablissements PaulDuclos, Le (Janet-Marseille, France, a "corporation of FranceApplication July 1, 1950, S.erialNo.'171 ',677

Claims priority, application France August 23, 1949 However, quiteserious-difficulty.is:encountered when it is desired to maintain aconstant tension on the cable regardless of the many and sundry hitchesthat inevitably occur during a cable laying operation. This .isespecially true when the ship has considerable ipitching motion orfurther when a deep change of :level occurs in the ocean bottom overwhich the cable is being laid.

The ships pitching movements, and changes :of level in the :oceanbottom, .loothzresult in considerable variations in the :rate "of freedof the :cable, producing inertia zstresses *which exert considerableinfluence of sthe tension to which the cabletis subjected.

In thecase of the ship's pitching, SU'ChKStI'GSSBS are substantiallyproportional to, and of opposite direction from, the :amplitude of thepitching motion responsible for them, that "the elon- :gation or:deviation f the ship from the horizontalplane.

Where a change of level occurs, .an increase in the rate of feed of thecable results and every change in the :gradient of the ocean bottombrings about .a substantial stress due to inertia. Most troublesomehowever .aresudden variations in depth, such as occur when .an oceandeep is encountered, because such variations .or .drops in level causethe cable to .unreel suddenly by a length equivalent to twice thevertical extent of the drop, with resulting inertia stresses ofconsiderable magnitude, .w'hich would quickly attain dangerous values.unless they are "taken up by adequate brakage.

The variations in cable tension due to variations in the rate of cablefeed areusually avoided by providing the cable drum with 'avariablebraking device. Thebraking action is controlled manually 01'automatically with regard to the variations in cable .feed, orpreferably as .a function of the acceleration of the cable, that is tosay as .a function of the actual cable tension resulting from suchvariations.

Hydraulic braking has already been suggested as the best isuitedior thispurpose, the braking effect being produced by the resistance of a pumpThis associated with 'the'c'able drum and arranged to exert a variableresistance corresponding with the variations in tensiono'f the cable.

To take up such variations, the solutionadvocated in the past was to usea pump havinga constant cylinder capacity and variable deliverypressure, by -means of which the braking-stress could be made to varythrough control *of 'the delivery pressure of the pump.

This variation in'the'delivery pressure' may be achieved by adjustingthe bias 'load of a valve interposed on the delivery o'f the pump. Thismethod however lacks accuracy, requires complicated structure to carryit into practice and is 'hardto work. *For-th'ese reasons it has neverbeen much'used.

It is generallypreferred to use a variable restriction interposed inthe-circuit of the volume- =pump, and adapted to create a variableresist- -ance and=consequently a variable pressure of the "fluiddelivered "by "the pump and thus a variable braking force, which canbemade'-to correspond with the variationsinthe pull-of'the cable. Thissolution while simpler "than the 'firstmentioned one, is not howeverwithout its serious short=- comings. The resistance opposed by therestriction to the flowo'ffluid, ther'ate of ilow of which is adjustedin accordance with the speed of the ship (which normally isthe same asthe 'r'a-te'of feed of the cable) dependson that speed. Consequently,the adjustment of the pressure which controls the braking force shouldbe made in correlation both with the tension of the cable :and with thespeed of'the ship. This resu'ltsin complication and lack of safety.

My present invention has for its object "to pro vide .a-method and means.for braking the feed of the cable whereby the above drawbacks areaverted and whereby the braking force may be made to correspondaccurately with the instantaneous tension of the cable, thusprovidinginstant compensation for any variation in :said tension in order toachieve 'a substantially constant tension regardless of anyirregularities encountered in the process-of cable-laying.

According to the invention, the rate of feed of the cable iscontrolled-or bra-ked by means of a pump having a variable cylindercapacity delivering fluid atconstant pressure. 'l he'bralcing stress iscontrolled by acting upon the cylinder capacity rather than upon thedelivery pressure of the pump. The cylinder capacity is adjusted tocorrespond at each instant with the tension of the cable, thuscompensating for any variation in said tension in a direct and immediatemanner.

The result is an accurate adjustment which is independent of the speedof the ship. The operation requires reduced muscular exertion and thenecessary equipment is simpler and less expensive.

The arrangement according to the invention lends itself to the provisionof automatic adjustment, in which the cylinder capacity is controlled bymeans of an accelerometer driven from the cable drum. The accelerometeris responsive to variations in the rate of feed of the cable, i. e. toaccelerations, and therefore to the inertia stresses to which the cableis subjected, and is made to control through any suitable means whichmay be mechanical, hydraulic or electrical in character, theinstantaneous rate of flow of the pump, the braking force developed bywhich will accordingly be varied in a manner directly corresponding tothe cause which is to be compensated for.

The accompanying drawings diagrammatically illustrate one form ofembodiment of the invention, given by way of a nonrestrictive example.

Fig. 1 is a general view of the cable feed mechanism.

Fig. 2 is a diagram of the braking device.

In the cable ship indicated by its outline l, the cable 2 unwound fromthe cable drums 3 arranged in the cable-tank, is wound around theunreeling or feed drum 4. Thence it is led over a set of rollers 5 tothe davit 6 arranged at the bows of the ship at the upper part of thestem, from which it runs down into the sea.

It is the drum 4 which controls the rate of feed of the cable by meansof a braking device diagrammatically indicated at 1. The braking forcemust be so adjusted as to maintain the tension of the cable, as measuredby dynamometer 8, at a constant value.

The braking device comprises a pump 9 of the variable cylinder capacitytype driven by the drum 4 (Fig. 2) through the medium of a reducer gearH). The pump 9 operates in a closed circuit I I. This circuit includes aconstant pressure valve [2 and a cooler [3 for dissipating the heat fromthe fluid under pressure.

The variable delivery or displacement pump 9 may advantageously be ofthe rotary type having radial or axial pistons, in which thedisplacement per revolution is controlled by altering the setting of thepistons relatively to a fixed distributor. However, any other suitabletype of variable delivery or variable displacement pump may be used.

The adjusting system of the pump 9 may be controlled from a control rodI4, thereby controlling the pumps cylinder displacement, while thepressure of delivery is maintained constant by the valve I2.

The arrangement allows of manual control, wherein the rod or lever I4 isactuated in accordance with the variations in tension of the cable 2. Inpractice, it is somewhat difficult for the operator to discern withclearness the variations in acceleration, and it will be sufiicient ifhe keeps to the indications supplied by the dynamometer 8 to make thenecessary maneuvers.

However, one of the chief advantages of the braking system according tothe invention is the simplicity with which it lends itself to automaticoperation. Thus, the delivery adjusting member H of pump 9 may becontrolled from the variations in tension of the cable as measured bythe dynamometer 8 and acting through a transmission at an appropriatedistance.

A more desirable method will consist of controlling the pump through thevariations in the rate of feed of the cable. For this purpose, anaccelerometer I5 is provided connected for movement with the drum 4, andthe movable or responsive element of the accelerometer is made tocontrol the adjusting member [4.

In the form of embodiment of Fig. 2, the accelerometer is of theinertia-acting type, for instance a structure of a type similar to thedampers used to damp vibrations in internal combustion engines.

The movable or responsive member of the accelerometer l5 actuates adistributor [6 which communicates through a pipe I! with the delivery ofthe pump 9.

The distributor controls the intake of liquid under pressure into acylinder 18 in which a piston I9 is movable. The piston l9 carries apiston rod l4 which actuates the eccentric displacement adjusting ringof the pump 9.

The accelerometer I5 is driven from the drum 4, as stated, and detectsany variations in acceleration to which the cable 2 may be subjected.Depending on the direction of this variation, the accelerometer acts onthe distributor 16 to move the double-acting piston [9 in one or theother direction, thereby causing the rate of delivery of the pump tovary in a direction corresponding to the braking force to be produced.

For example, if for any reason the cable tension increases so as toaccelerate the drum, then the accelerometer 15 operates the valve [6 tosupply fluid to cylinder I8 and move the piston 19 in a direction todecrease the pump delivery. The braking action is therefore decreasedand the decrease in the pump delivery and the braking action continuesuntil such time as the acceleration of the cable stops. The tension inthe cable is relieved by reducing the braking action during periods ofan accelerated cable movement. In a similar manner, the braking actionis increased during deceleration of the cable so as to maintain thetension in the cable and prevent it from becoming slack.

An automatic braking effect is thus obtained which is in directcorrelation with the positive or negative accelerations in the feed ofthe cable Provision should be made for eliminating automatic operationand reverting to manual control in the case of diflicult or criticaloperations. Furthermore, means should be provided for instantaneouslyshort-circuiting the automatic system in case of an emergency requiringinstantaneous action.

It will be understood that while a hydraulic control was illustrated foradjusting the delivery of the pump 9, electrical or mechanical means maybe employed instead.

What I claim is:

1. Apparatus for regulating the tension in a cable to maintain saidtension substantially constant, comprising a drum about which the cableis wound, a variable delivery pump connected to said drum to be driventhereby, means for regulating the discharge pressure of said pump at asubstantially constant value, a closed liquid circuit including saidpump, a cooling coil in said circuit for dissipating heat from theliquid therein, an accelerometer driven by said pump, and means operatedby the accelerometer for decreasing the delivery of the pump in responseto acceleration of the drum and increasing the pump delivery in responseto deceleration of the drum.

2. Apparatus for regulating the tension in a cable to maintain saidtension substantially constant, comprising a drum about which the cableis wound, a variable delivery pump connected to said drum to be driventhereby, means for regulating the discharge pressure of said pump at asubstantially constant value, a closed liquid circuit including saidpump, a cooling coil in said circuit for dissipating heat from theliquid therein, an accelerometer driven by the drum, a liquiddistributor valve operated by the accelerometer and supplied with liquidfrom said pump, a double acting cylinder controlling the delivery of thepump, said cylinder being supplied with liquid by said distributorvalve, said accelerometer, distributor valve and cylinder cooperating todecrease the delivery of the pump in response to acceleration of thedrum and increase the pump delivery in response to deceleration of thedrum.

3. Apparatus for regulating the tension in a cable to maintain saidtension substantially constant, comprising a drum about which the cableis Wound, a variable delivery pump connected to said drum to be driventhereby, means for regulating the discharge pressure of said pump at asubstantially constant value, a closed liquid circuit including saidpump, an accelerometer driven by said pump, and means operated by theaccelerometer for decreasing the delivery of the pump in response toacceleration of the drum and increasing the pump delivery in response todeceleration of the drum.

MARC GALIN.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 21,371 Scott Aug. 31, 1858 635,235 Christ Oct. 17, 18991,106,588 Schnitzler et a1 Aug. 11, 1914 2,091,418 Schoene Aug. 31, 19372,244,830 Doe et a1 June 10, 1941 2,249,947 Doe July 22, 1941 2,261,261Kubera Nov. 4, 1941 2,402,789 Tweedale June 25, 1946

